Accurate automotive engine control requires accuracy in modeling the physical character of the engine, its components and parts under all engine operating conditions. Engine parameters such as temperature, pressure, mass, etc. are currently used to characterize the physical character of an engine. A substantial investment has been made in accurate sensing, estimating, or predicting of such engine parameters. Nonetheless, there remain engine operating conditions in which model errors persist, reducing engine control performance under such operating conditions. One example of such an operating condition is an engine startup condition following an engine latency period. It is common to preserve reserve electrical power, such as automotive vehicle battery power by disabling parameter sensors, estimators and predictors during engine latency periods. As such, variation in changing engine parameters, such as temperature parameters, is not logged during engine latency periods. Further, it is not economical or may not be technically feasible to measure every engine parameter of interest in engine control. Many engine parameters may be, under most operating conditions, accurately estimated using related measured engine parameter values. For example, under steady state engine operating conditions, engine cylinder temperature, engine intake valve temperature, and engine cylinder intake runner temperature may correspond well to measured engine coolant temperature. As such, most of the time during engine operation, a reasonable estimate of such temperatures is available simply by sensing coolant temperature. However, under engine startup conditions (which present many well-documented control stability, smoothness and efficiency challenges), the engine coolant temperature-based model of the temperature of such engine parts as intake runners, cylinders and intake valves, often is very inaccurate. The thermal time constant associated with the engine coolant system is significantly different than that of such other engine parts. Accordingly, such engine parts may heat up or cool down much more rapidly than engine coolant. For example, under a short run condition, when the engine has run a short time, is shut down for a short time and then is restarted, engine coolant may be at a low value, while certain engine parts may be fully elevated in temperature. A coolant temperature-based model will then be inaccurate.
The temperature of such engine parts as cylinders, intake valves intake runners, and fuel injector has a significant effect on the mixing and vaporization characteristic of an engine air/fuel mixture. Engine fueling control must account for the temperature of such parts to provide for accurate engine fueling, as is required for acceptable engine performance and emissions. Under engine startup conditions, such cannot be provided under conventional approaches relying on engine coolant temperature-based modeling.
It would therefore be desirable to accurately estimate the temperature of such engine parts following an engine latency period without incurring the cost and complexity associated with sensing temperature of every engine part or component to which the engine control is sensitive.